The purpose of this study is to describe the motions of the tongue and jaw during feeding. Prior studies of mastication in man have focused on the motions of the teeth and jaws, but the role of the tongue in food transport and positioning and the oral stage of swallowing have been neglected. Motions of the jaw, tongue, and palate have characteristic patterns in macaque and lower mammals, which vary with the consistency of the food. Our preliminary studies show similar patterns in man. We will expand our current studies by determining the spatial and temporal relationships between tongue and jaw motion cycles, and how these motions are influenced by the initial food consistency and stage in sequence (from ingestion to terminal swallow). We will use videofluorography in the lateral and postero-anterior projections to study forty normal subjects eating soft and hard solid foods. Small radiopaque markers will be glued to the surface of the tongue to demonstrate its motions. Twenty subjects will have midline tongue markers and twenty will have triangulated markers. For half the subjects in each group, food will be combined with barium to reveal its movement relative to oral and pharyngeal structures. The progression of the bolus through the foodway and the overall movement patterns of the jaw, hyoid bone, and tongue will be evaluated by reviewing the videotapes in slow motion. Selected sequences will be digitized with image processing software and the Cartesian coordinates for the jaw, hyoid bone, and tongue, jaw reference points established. Computer graphics will be used to display motion of these structures over time. Data analysis will establish the spatial and temporal relationships of the jaw, tongue, and hyoid bone, and how these are influenced by both initial food consistency and stage (from ingestion to terminal swallow). Movements of the tongue in the coronal plane will be analyzed as a measure of tongue rotation during chewing. Descriptive and analytical statistics will be used to develop a multivariate model for tongue-jaw behavior and to examine current models for neural control of mastication and swallowing. This knowledge is essential to understanding the motor control for mastication and swallowing and will ultimately lead to progress in the evaluation and treatment of dysphagic individuals.